Circuit breaker with spring-biased toggle link



"Nov. 22, 1966 R. T. CASEY 3,287,522

CIRCUIT BREAKER WITH SPRING-BIASED TOGGLE LINK Filed June 28, 1965 2sheets-sheet 1 INVENTOR.

R. T. CASEY Navy 22, 1966 CIRCUIT BREAKER WITH SPRING-BIASED TOGGLE LINKFiled June 28, 1965 2 Sheets-Sheet 2 United States Patent 3,287,522CIRCUIT BREAKER WITH SPRING-BIASED TOGGLE LINK Robert T. Casey,Southington, Conn., assignor to General Electric Company, a corporationof New York Filed June 28, 1965, Ser. No. 467,354 6 Claims. (Cl. 200116)The present invention relates to improved circuit breakers and moreparticularly to a novel circuit breaker of the type which may bemanually operated to either the open or the closed position and whichmay be automatically operated to the tripped position in response to anoverload in the circuit to which it is connected.

It is an object of this invention to provide an improved circuit breakerwhich is relatively compact and rugged and which is relativelyeconomical to manufacture.

A specific object of this invention is to provide a simple and compactcircuit breaker that utilizes a toggle mechanism with a sliding linkbiased by a compression spring to position a contact arm pivoted on areleasable member in the open, closed and tripped position.

It has now been found that the foregoing objects and other advantagescan readily be attained in a circuit breaker for manual operation duringnormal use and for automatic operation in response to an overload in thecircuit having a housing with a manually operable switch pivoted betweenits ends on the housing and a releaseable member pivoted on the housing.A fixed contact is supported on the housing, and a contact arm providinga movable contact for engagement with the fixed contact is pivotablymounted for rotation about a point on the releasable member into aclosed position with its movable contact in engagement with the fixedcontact and into an open position away therefrom. A toggle link betweenthe switch and the contact arm, biased by a compression spring positionsthe cont-act arm and is manually operable by the switch.

Switch means in the housing responsive to current overload or othermeans normally holds the releasable member in fixed position but isoperable to free the releasable member for pivoting within the housingto move the contact arm away from the fixed contact. A compressionspring operating between the switch and contact arm biases the contactarm and the releasable member and cooperates with the switch and atoggle link engaged with the switch and contact arm to provide a togglewith the spring biasing the toggle link to pivot the contact arm into aclosed position with its movable contact in engagement with the fixedcontact and into an open position spaced therefrom upon operation of theswitch.

In this circuit breaker, the toggle link is slidably engaged at one endand pivotably engaged at the other end, with the sliding engagementpreferably being provided at the contact arm for ease of constructionand assembly and for economy. The switch, slidable toggle link andcompression spring form a compact toggle device for biasing the contactarm into the desired position. When the circuit breaker is manuallyoperated to the open position, the line of action of the compressionspring is moved across the pivot point of the contact arm so that thearm is biased toward the open position. The force of the compressionspring on the contact carryice ing arm also tends to bias the cradlemember in a clockwise direction. If an overload occurs while the switchand contacts are in the closed position, the free end of the cradlemember will be released by thermally responsive bimetallic stripor otheroverload responsive switch means and the cradle member will rotate in aclockwise direction. In this manner, the pivot point of the contact armis moved across the line of action of the compression spring and, asthis occurs, the compression spring biases the toggle link which movesthe contact arm down and away from the fixed contact. In accordance withconventional practice, the switch means or latch for holding thereleasable member in .a fixed position may be any of the types wellknown in the art and is responsive to a current overload, and it mayalso be manually operable. The position of the toggle link may bereversed and the same results obtained by having one end of the linkpivoted on the contact and its opposite end slidably engaged with themanually operable switch by seating in an aperture or recess formedtherein.

The circuit breaker mechanism is constructed so that the parts operatein a relatively small volume because the parts are interfit-ted in anovel and highly desirable manner. The toggle link is disposed withinthe compression spring, which in turn is partially contained within thelegs of the releasable member. Thus, within a relatively small volumeall the operating parts are interfitted to form a compact mechanism thatis relatively inexpensive to manufacture and efficient in operation.

For a more complete understanding of the invention, reference is nowmade to the following detailed specification and to the accompanyingdrawings in which:

FIGURE 1 is a side elevational view partly in section of the circuitbreaker incorporating the invention with certain portions of theenclosing casing being removed to show internal construction and withmovable elements of the structure being shown in the manually operatedopen condition;

FIGURE 2 is a view similar to FIGURE 1 with the movable elements beingshown in the closed condition;

FIGURE 3 is a view similar to FIGURE 1 With the movable elements beingshown in the condition assumed upon operation by an overload current;and

FIGURE 4 is an exploded view in perspective of some of the movableelements of the circuit breaker of FIG- URES 1-3.

Referring now in detail to the attached drawings, therein illustrated isa preferred embodiment of the present invention wherein the circuitbreaker has a housing of nonconducting material, generally designated bythe numeral 10, with end wall 12 providing a laterally extendingshoulder 14 upon which is pivotably mounted the pivot portion 16 of thereleasable member or cradle, generally designated by the numeral 18. Thepivot portion 16 has arms 20 extending laterally which seat in recesses22 in the sidewalls 24 of the housing. As best seen in FIGURE 4, thecradle 18 has an extended leg portion 26, a shorter leg portion 27, anda bridging bar portion 28 of which the pivot portion 16 is a part.

Pivotably seated within the notches 30 in the upper edge of the legportions 26 and 27 of the cradle 18 are the outwardly projecting fingers32 at the upper end of the contact arm generally designated by thenumeral 34 which is partially surrounded by and rotatable partiallywithin the legs 26 and 27 of the cradle 18. As best seen in FIGURE 4,the contact arm 34 has a pair of leg port-ions 36 connected by a baseportion 38 and a stiffening portion 42 intermediate the length thereof.The base portion 38 carries a movable contact 44 having a slot 46therein and connected to the flexible cable 48.

Pivotably mounted within an aperture 50 in the end wall 52 of thehousing is a switch of nonconducting material generally designated bythe numeral 54 and having pivot arms 56 which seat in the sidewalls 24of the housing 10. Extending outwardly of the aperture 50 in end wall 52is a manually operable handle portion 58 on the switch 54 which also hasan inner end 60 with a recess providing shoulders or recess portions 62for pivotally seating the arms '64 at the end of the sliding linkgenerally designated by the numeral 66. A compression spring 70 extendsabout the sliding link 66 and is held by the cross bar portion 68thereof against the movable contact 44, all partially within the legportions 36 of the contact arm 34. The sliding portion 72 at the otherend of the sliding link 66 slidably seats within the slot 46 in themovable contact 44.

Thus a compact operating mechanism is efliciently and economicallyconstructed by having the sliding link 66 positioned within thecompression spring 70, which in turn is partially contained within theleg portions 36 of the contact arm 34, and these parts are all retainedpartially within the leg portions 26 and 27 of the cradle 18.

The sliding link 66 and switch 54 form a toggle linkage biased bycompression spring '70 for moving contact arm 34 to either the open orthe closed position and for moving cradle 18 to the tripped position.When contact arm 34 is rotated from the open position illustrated inFIGURE 1 to the closed position illustrated in FIGURE 2 by manuallypivoting handle portion 58 of switch 54 in a counterclockwise direction,the sliding link 66 and the line of action of compression spring 70 aremoved across the pivot point of contact arm 34 at the notches 30 on thecradle 18. This rotation of switch 54 causes the toggle link 66 to slidefarther into the slot 46 whereby the spring 70 is compressed betweencrossbar 68 on the sliding link 66 and the movable contact 44 on thecontact arm 34. Thus when the toggle linkage is straightened and thenbuckles in the opposite direction the sliding portion 72 of the slidinglink 66 applies force to the wall of the contact 44 at the end of theslot 46 and rotates the contact arm 34 to the closed positionillustrated in FIGURE 2.

This action described above is reversed when it is desired to move thecontact arm 34 from the closed to the open position. The rotation of thecontact arm 34 when moved to the open position is limited by the stop 73on the sidewall 24 of the housing 10.

The cradle 18 is normally held in the fixed position shown in FIGURES 1and 2 between the shoulder 14 and the releasable member or latch 74which has a shoulder portion 76 supporting'the extended leg portion 26.The compression spring 70 biases the contact arm 34 against the cradle18 at the notches 30 and thereby tends to move the cradle 18 in aclockwise direction about the pivot portion 16 as viewed in FIGURE 1 butis restrained from such movement while the shoulder portion 76 of thereleasable latch 74 engages the leg portion 26. The shoulder portion 76of latch 74 is normally held in the position illustrated in FIGURE 1 bythe spring 77 attached to the wall member 79 which biases the latch 74toward the cradle 18.

The releasable latch 74 has arms 75 at one end thereof pivotably seatedin recesses 78 in end wall 52 and may be automatically operated by anoverload releasing means such as the current-responsive, thermallyactuated, bimetallic strip 80 which will bend away from the releasablelatch 74 upon the occurrence of predetermined overload currentconditions. The bimetallic strip 80 is connected to the load terminal 82and to the flexible cable 48. When the bimetallic strip 80 is actuatedby an over- 4, load current, it bends and engages clip 84 attached tothe latch 74 to move the latch 74 against the bias of the spring 77 andthe shoulder portion 76 of the latch 74 is moved away from and releasesthe extended leg portion 26 of cradle 18.

As the latch 74 is tripped by the movement of the bi metallic strip 80due to current overload and the cradle 18 is released and rotatesdownwardly about the pivot portion 16 on the shoulder 14 of the housing10 where it is supported in the tripped position by the stop 73 on thehousing 10, the fingers 32 of the contact arm 34 cross the line ofaction of the compression spring whereby the toggle linkage formed bythe switch 54 and sliding link 66 is straightened and then biased into abuckled position in the opposite direction by the force of the spring70, moving the contact arm 18 to open to the tripped positionillustrated in FIGURE 3. The rotation of the switch 54 moves the handleportion 58 thereof into a straight-up position indicating that themechanism has been tripped.

The cradle 18 may be reset to the fixed position after tripping hasoccurred when the bimetallic strip has cooled and the latch 74 has beenreturned to its normal position by the force of spring 77 by manuallyrotating the switch 54 in a clockwise direction from the trippedposition illustrated in FIGURE 3 to the open position illus trated inFIGURE 1 whereby the inner end 60 of the switch 54 engages the bridgingbar portion 28 of the cradle 18 to rotate it upon its pivot portion 16until the shoulder portion 76 of the latch 74 engages the end of theextended leg portion 26 of the cradle 18 to retain it in the fixedposition.

In accordance with conventional practice, the housing 12 also has a lineterminal 83 electrically connected to the fixed contact 86 so that whenthe contact arm 34 is in the closed position illustrated in FIGURE 2 anelectric circuit is completed between the line terminal 83 and the loadterminal 82 so that current may pass through the fixed contact 86 to themovable contact 44 where it is conducted to the flexible cable 48 andthen through the bimetallic strip 81) to the load terminal 82. An arcchute 90 is also provided on housing 10 about the path of the movablecontact 48 to and from the fixed contact 86.

Thus, it can be seen that the present invention provides a novel circuitbreaker which is relatively compact and rugged and relatively economicalto manufacture. The interfitting of parts and the novel assembly withits compression spring provides a highly efiicient structure within asmall volume, permitting considerable variation in design andapplication.

While the invention has been described in only one particular form itwill be appreciated that many modifications thereof may be made withoutdeparting from the spirit of the invention. I therefore intend, by theappended claims, to cover all modifications as fall within the truespirit and scope of the invention.

1. An electric circuit breaker comprising:

(a) a support;

(b) a stationary contact supported in fixed relation on said support;

(0) a releasable cradle member pivotally supported on said support;

(d) a movable contact member;

(e) means pivotally supporting said movable contact member on saidreleasable cradle member at a pre determined point;

(f) a manually operable handle member;

(g) means pivotally supporting said manually operable handle means onsaid support for rotation about a predetermined axis of rotation;

(h) spring means connected between a first point on said manuallyoperable handle member eccentric to said axis of rotation and a secondpoint on said movable contact member spaced from said predeterminedpoint, said spring means urging said first point and said second pointapart;

(i) latch means normally restraining said cradle member from rotationabout its pivotal support;

(j) current responsive means carried by said support;

(k) means connecting said current responsive means to said latch means,said current responsive means causing release of said latch means uponthe occurrence of predetermined current conditions therethrough.

2. An electric circuit breaker comprising:

(a) an insulating casing;

(b) at least one stationary contact supported in said insulating casing;

(c) a releasable cradle member pivotally mounted in said casing at apredetermined pivot point;

(d) an elongated movable contact member pivotally supported on saidreleasable cradle member at a second pivot point spaced from said firstpivot point said movable contact member having a contact surface spacedfrom said second pivot point for cooperating with said relativelystationary contact, said movable contact member extending to a firstside of said releasable cradle member;

(e) a manually operable handle member pivotally supported in said casingat a side of said releasable cradle member opposite from said first sideand including a first manually operable portion projecting from saidpivot point outside of said casing for manual operation of said switchmember and havinga second portion extending in a direction opposite tosaid first direction;

(f) spring means connected between a first point of said second portionof said manually operable member and a second point of an intermediateportion of said movable contact member and urging said first point andsaid second point apart and acting through said movable contact memberto tend to cause rotation of said releasable cradle member about itspivotal support;

(g) latch means normally engaging and restraining said releasable cradlemember from rotation about its pivotal support under the influence ofsaid spring means;

(h) current responsive means connected electrically in series with saidstationary and movable contacts; (i) means connecting said currentresponsive means to said latch means, said current responsive meanscausing release of said latch means upon the occurrence of predeterminedcurrent conditions through said contacts said spring means when releasedmoving said releasable cradle member in a direction away from saidmanually operable member to move said second pivot point across the lineof action of said spring means to reverse the bias of said spring meansupon said movable contact member.

3. An electric circuit breaker comprising:

(a) a housing;

(b) a manually operable handle pivoted between its ends on said housing;

(c) a releasable member pivoted on said housing;

(d) a fixed contact;

(e) a contact arm pivoted for rotation about a point on said releasablemember and providing a movable contact for engagement with said fixedcontact, said contact arm being pivotable into a closed position withits movable contact in engagement with said fixed contact and pivotableinto an open position away therefrom;

(f) latch means in said housing normally holding said releasable memberin fixed position but operable to free said releasable member forpivoting within said housing to move said contact arm away from saidfixed contact;

(g) a compression spring acting between a first point of said manuallyoperable handle and a second point of said contact arm for biasing saidcontact arm and 6 said releasable member, said spring urging said firstand second points apart;

(h) a toggle l-ink engaged with said manually operable handle andcontact arm and cooperating with said spring to pivot said contact arminto a closed position with its movable contact in engagement with saidfixed contact and into an open position spaced therefrom said togglelink being a normally operable handle.

4. An electric circuit breaker is set forth in claim 3 wherein saidtoggle link is slidably engaged at one end and pivotally engaged at theother end thereof.

5. An electric circuit breaker for manual operation during normal useand for automatic operation in response to an overload in the circuitcomprising:

(a) a housing;

(b) a manually operable handle pivoted between its ends on said housing;

(c) a releasable member pivoted on said housing;

(d) .a fixed contact;

(e) a contact arm pivoted for rotation about a point on said releasablemember and providing a movable contact for engagement with said fixedcontact, said contact arm being pivotable into a closed position withits movable contact in engagement with said fixed contact and pivotableinto an open position away therefrom;

(f) latch means in said housing normally holding said releasable memberin fixed position but operable upon current overload to free saidreleasable member for pivoting within said housing to move said contactarm away from said fixed contact;

(g) a sliding link having one end thereof pivoted on one end of saidmanually operable switch and the other end thereof in sliding engagementwith one end of said contact arm for pivoting said contact arm into aclosed position with its movable contact in engagement with said fixedcontact and into an open position spaced therefrom, said sliding linkbeing normally operable by said manually operable switch into either ofsaid positions;

(h) a compression spring having its ends operating against said slidinglink and said contact arm for biasing said contact arm and saidreleasable member into an open and closed position.

6. An electric circuit breaker for manual operation during normal useand for automatic operation in response to an overload in the circuitcomprising:

(a) a housing;

(b) a manually operable handle pivoted between its ends on said housing;

(c) a releasable member pivoted on said housing;

(d) a fixed contact;

(e) a generally U-shaped contact arm partially enclosed by saidreleasable member and pivoted for rotation in notches on said releasablemember and providing a movable contact for engagement with said fixedcontact, said contact arm being pivotable into a closed position withits movable contact in engagement with said fixed contact and pivotableinto an open position away therefrom;

(f) switch means in said housing normally holding said releasable memberin fixed position but operable upon current overload to free saidreleasable member for pivoting within said housing to move said contactarm away from said fixed contact;

(g) a sliding link having one end thereof pivoted on one end of saidmanually operable handle and the other end thereof in sliding engagementwith one end of said contact :arm for pivoting said contact arm into aclosed posit-ion with its movable contact in engagement with said fixedcontact and into an open position spaced therefrom, said sliding linkbeing normally operable by said manually operable switch into either ofsaid positions; and

7 8 (h) a compression spring partially enclosed by said con- 3,110,78611/ 1963 Glezheizer 200116 X tact arm and partially surrounding saidsliding link, 3,171,921 3/1965 Woods. said spring having its endsoperating against said slid- 3,201,550 8/ 1965 Leonard 200116 X ing linkand said contact arm for biasing said contact Referenees Cited bv theApplicant arm and said releasable member in opposite rotative 5directions and for biasing said contact arm to open UNITED STATESPATENTS and closed positions, 2,190,517 2/1940 Jennings. 2,214,695 9/1940 Jennings. References Cited by the Examiner 2,624,815 1/1953 GanoUNITED STATES PATENTS 10 2,627,563 2/1953 Thomas.

2,688,675 9/1954 Casey. 2,174,232 9/1939 Baker 200-1 16 2 473 4 1949Baxter 200 116 BERNARD A. GILHEANY, Przmary Exammer.

2,902,560 9/1959 Stanback et al 20088 H. B. GILSON, Assistant Examiner.

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING: (A) A SUPPORT; (B) ASTATIONARY CONTACT SUPPORTED IN FIXED RELATION ON SAID SUPPORT; (C) ARELEASABLE CRADLE MEMBER PIVOTALLY SUPPORTED ON SAID SUPPORT; (D) AMOVABLE CONTACT MEMBER; (E) MEANS PIVOTALLY SUPPORTING SAID MOVABLECONTACT MEMBER ON SAID RELEASABLE CRADLE MEMBER AT A PREDETERMINEDPOINT; (F) A MANUALLY OPERABLE HANDLE MEMBER; (G) MEANS PIVOTALLYSUPPORTING SAID MANUALLY OPERABLE HANDLE MEANS ON SAID SUPPORT FORROTATION ABOUT A PREDETERMINED AXIS OF ROTATION;